Project Summary: Transitional cell carcinoma of the bladder (TCC) ranks 4th in incidence of all cancers in the developed world, yet the mechanisms of its origin and progression remain poorly understood. There are also few useful diagnostic or prognostic biomarkers for this disease. The long-term aim of this proposal is to determine molecular mechanisms involved in early and late steps in the development of TCC. In addition we hope to identify new biomarkers for detection, diagnosis and prognosis of TCC. To accomplish this we will use a mouse model for bladder cancer in which the SV40 large T antigen (SV40 T) is expressed under the control of the uroplakin promoter, which restricts expression to the bladder urothelium. These mice (UPII- SV40T) develop TCC, which is preceded by a condition resembling human CIS. The hypothesis underlying this proposal is that there are differences in gene expression profiles and gene regulatory networks between invasive TCC and CIS and between CIS and distant normal appearing urothelium, and that these changes are indicative of the malignant state. This hypothesis is based on the multistep carcinogenesis concept. An extension of our hypothesis is that CIS is an intermediate step between normal urothelium and invasive TCC and that there should be changes in gene expression corresponding to this intermediate state. The specific aims are: 1. Identify the genes and gene regulatory networks that are differentially expressed between the normal urothelium of nontransgenic and UPII-SV40T mice, CIS and TCC, using Affymetrix GeneChip(r) Arrays. The relevence of individual genes to human TCC will be validated by assessing expression of the human homologs in patient TCC and normal urothelium specimens. In silico analysis of the microarray data, which includes generating gene expression profiles (clustering analysis) and the development of promoter models based on the promoter sequences of the differentially expressed genes will be performed. 2. Assess the function and potential relevance to bladder carcinogenesis of these genes in vivo by stable overexpression, or siRNA-mediated suppression, of the validated genes in human bladder-derived cell lines. Relevence: Completion of these studies should advance our understanding of the molecular events underlying TCC development. In addition, the identification of genes differentially expressed between normal urothelium, CIS and TCC will provide much needed diagnostic and prognostic markers for this disease. [unreadable] [unreadable] [unreadable]